Chapter 12.9, Problem 16IP

To determine

To find : Ratio between surface area of Penny and Nickel.

Answer to Problem 16IP

  $\frac{79}{100}$

Explanation of Solution

Given information :

The given information is, Diameter of Penny ( $d_1$ ) = $19.05$ mm

Diameter of Nickel ( $d_2$ ) = $21.21$ mm

Height of Penny ( $h_1$ ) = $1.55$ mm

Height of Nickel ( $h_2$ ) = 1.95 mm

Formula Used:

Surface Area (SA) of cylinder = $2\pi rh+2\pi r^2$

Calculation :

Surface Area of Nickel

  $\begin{array}{l}=2\times 3.14\times \frac{21.21}{2}\left(\frac{21.21}{2}+1.95\right)\\ =3.14\times 21.21\times (12.56)\\ =836.49{\text{ mm}}^{\text{2}}\end{array}$

Surface Area of Penny

  $\begin{array}{l}=2\times 3.14\times \frac{19.05}{2}\left(\frac{19.05}{2}+1.55\right)\\ =59.817(11.075)\\ =662.47{\text{ mm}}^{\text{2}}\end{array}$

Ratio between Sa of Penny and Nickel

  $=\frac{662.47}{836.49}=\frac{79}{100}$